JP4631474B2 - Droplet discharge head and droplet discharge apparatus - Google Patents

Description

  The present invention relates to a droplet discharge head having a nozzle that discharges a droplet, a pressure chamber that communicates with the nozzle and is filled with a liquid, and a pool chamber that stores a liquid to be supplied to the pressure chamber, and the droplet The present invention relates to a droplet discharge device including a discharge head.

  Conventionally, ink droplets are selectively ejected from a plurality of nozzles of an ink jet recording head (hereinafter sometimes simply referred to as “recording head”) as a droplet ejection head, and characters, images, etc. are recorded on a recording medium such as recording paper. Inkjet recording apparatuses for printing are known.

  By the way, in an ink jet recording apparatus, normally, ink is once supplied from an ink tank to an ink pool chamber, and then supplied from an ink pool chamber to an ink discharge nozzle through a supply path.

  In recent years, the inkjet recording head having such a configuration is required to be capable of high-resolution printing while being low-cost and small. In order to meet this requirement, it is necessary to arrange the nozzles at a high density. For this reason, for example, in the liquid ejection device described in Patent Document 1, liquid is supplied from the ink pool chamber (liquid reservoir) to the nozzles. For this purpose, the arrangement pitch of the supply ports is made larger than the arrangement pitch of the nozzles. However, in the technique described in Patent Document 1, since the liquid reservoir is provided for each nozzle, the arrangement pitch of the supply ports cannot be reduced, and as a result, the head size increases. .

On the other hand, if the ink pool chamber is made common for supplying ink to a plurality of nozzles in order to reduce the size of the ink jet recording head, the ink pool chamber becomes insufficiently rigid and warps and deforms due to residual stress during the assembly process. The occurrence of problems such as bending and vibration during the discharge operation is also conceivable. In particular, the so-called Full Width Array (FWA), which enables image recording over the entire width of the recording paper, has a large ink jet recording head size, and the above problem becomes remarkable.
JP 2002-286735 A

  In view of such problems, the present invention provides a droplet discharge head that can increase the density and size of the nozzle and ensure rigidity, and a droplet discharge device including the droplet discharge head. The purpose is to provide.

  In order to achieve the above object, a liquid droplet ejection head according to claim 1 of the present invention includes a plurality of nozzles arranged at equal intervals in a predetermined direction and ejecting liquid droplets, and each of the plurality of nozzles. And a common pool chamber for storing the liquid to be supplied to the plurality of pressure chambers, and a plurality of supply holes for supplying the liquid to each of the pressure chambers are formed. A common pool chamber member and a reinforcing member that reinforces the strength of the common pool chamber member, wherein at least some of the plurality of supply holes are provided with one adjacent supply hole. It is arranged at a position where the distance is longer than the distance to the other supply holes adjacent to each other, a long interval region is formed between the long interval supply hole and the adjacent one supply hole, and the common pool chamber member The reinforcing member is disposed in the long interval region. It is characterized in.

  In the first aspect of the present invention, the common pool chamber stores liquid to be supplied to the plurality of pressure chambers, that is, the common pool chamber is common to the plurality of pressure chambers. Compared with the case where the chamber is formed, the supply holes for supplying the liquid from the common pool chamber to the nozzles can be arranged at a high density corresponding to the nozzles arranged at a high density. Therefore, the common pool chamber member constituting the droplet discharge head can also be reduced, and the droplet discharge head can be reduced in size.

  By the way, in this invention, in order to reinforce the intensity | strength of a common pool room, the reinforcement member is provided in the common pool room. It is difficult to arrange the reinforcing members between the supply holes arranged at high density. For example, as shown in FIG. 11, the reinforcing members are arranged at positions corresponding to the pressure chambers C according to the pitch of the nozzles N. If the supply holes A are arranged at intervals, the reinforcing member B blocks the supply holes. Therefore, as shown in FIG. 10, it can be considered that the width of the reinforcing member itself is narrowed so as not to block the supply hole A, but this makes it difficult to increase the rigidity of the common pool chamber member.

  Therefore, in the first aspect of the present invention, at least a part of the plurality of supply holes is a long-interval supply hole, and the distance from one adjacent supply hole is a distance from another adjacent supply hole. Place it farther away. Therefore, the distance between the long interval supply hole and the adjacent one supply hole becomes long, and a long interval region is formed. And a reinforcing member is arrange | positioned in this long space | interval area | region.

  Thereby, compared with the case where the supply holes are aligned, the width of the reinforcing member can be widened, the rigidity of the common pool chamber member can be increased, and the rigidity of the droplet discharge head is ensured. Can do.

  According to a second aspect of the present invention, in the liquid droplet ejection head according to the first aspect, the plurality of nozzles are arranged in a matrix.

  As described above, when the plurality of nozzles are arranged in a matrix, it is particularly difficult to dispose the reinforcing member. Therefore, the droplet discharge head according to claim 1 is preferable. Further, in the head in which the nozzles are arranged in a matrix, the head width becomes larger than that in the case where the nozzles are arranged in a row, so that there is a problem that the rigidity is easily lowered. However, rigidity can be effectively secured.

  The droplet discharge head according to claim 3 is the droplet discharge head according to claim 2, wherein the supply holes for at least one row are the long interval supply holes, and the reinforcing member is the common pool chamber member. It arrange | positions so that the width direction may be crossed, It is characterized by the above-mentioned.

  According to the said structure, since the reinforcement member is arrange | positioned so that the width direction of a common pool chamber member may be crossed, a common pool chamber member can be reinforced effectively.

  The droplet discharge head according to claim 4 is the droplet discharge head according to claim 3, wherein the reinforcing member is a partition that divides the common pool chamber into a plurality of pool chambers. It is what.

  According to the above configuration, the reinforcing member also serves as the partition, and the common pool chamber is divided by the partition and the capacity of each pool chamber is reduced. Therefore, the liquid flow in the pool chamber can be made smooth. In addition, if there is a large difference in the distance between the inlet for injecting ink into the common pool chamber and each supply hole, it will cause a difference in flow path resistance and cause discharge characteristics variation. Can be made more uniform.

  The droplet discharge head according to claim 5 is the droplet discharge head according to claim 3, wherein the reinforcing member is a rectifying plate constituting a liquid flow path in the common pool chamber. It is a feature.

  According to the above configuration, since the reinforcing member also serves as the current plate, the flow of the liquid in the common pool room can be made smooth, and the discharge of mixed bubbles and dust can be improved. Ink consumption can be reduced.

  The droplet discharge head according to claim 6 is the droplet discharge head according to any one of claims 1 to 5, wherein the nozzle is communicated with the nozzle as viewed from the droplet discharge direction. The relative positional relationship between the pressure chamber and the supply hole for supplying a liquid to the pressure chamber is the same in all combinations.

  According to the above configuration, the relative positional relationship among the pressure chambers, nozzles, and supply holes constituting the ejector is the same for all the ejectors. Therefore, there is a variation in droplet discharge characteristics due to the different relative positional relationship. It does not occur, and uniform droplets can be discharged.

  A droplet discharge device according to a seventh aspect includes the droplet discharge head according to any one of the first to sixth aspects.

  According to the above-described liquid droplet ejection apparatus, the rigidity of the liquid droplet ejection head can be ensured, so that a highly reliable liquid droplet ejection apparatus can be obtained.

  As described above, according to the present invention, it is possible to increase the density and size of the nozzles of the droplet discharge head and to ensure rigidity.

  As shown in FIG. 1, the ink jet recording apparatus 10 includes a sheet supply unit 12 that feeds out a sheet, a registration adjustment unit 14 that controls the attitude of the sheet, a recording head unit 16 that forms an image on a sheet by ejecting ink droplets. The recording unit 20 includes a maintenance unit 18 that performs maintenance of the recording head unit 16, and a discharge unit 22 that discharges a sheet on which an image is formed by the recording unit 20.

  The sheet supply unit 12 includes a stocker 24 in which sheets are stacked and stocked, and a transport device 26 that transports the sheets one by one from the stocker 24 to the registration adjusting unit 14.

  The registration adjusting unit 14 includes a loop forming unit 28 and a guide member 29 for controlling the posture of the paper. By passing through this portion, the skew is corrected using the stiffness of the paper and the conveyance timing is controlled. The recording unit 20 is entered.

  The discharge unit 22 stores the sheet on which the image is formed by the recording unit 20 in the tray 25 via the discharge belt 23.

  Between the recording head unit 16 and the maintenance unit 18, a paper conveyance path 104 for conveying the recording paper P is configured (the conveyance direction is indicated by an arrow H). The recording paper P is sandwiched between the star wheel 17 and the transport roll 19 and transported continuously (without stopping). Then, ink droplets are ejected from the recording head unit 16 to the paper, and an image is formed on the recording paper P.

  The maintenance unit 18 includes a maintenance device 21 that is disposed to face the ink jet recording head 32, and can perform capping, wiping, dummy jet, vacuum processing, and the like on the ink jet recording head 32.

  As shown in FIG. 2, each of the inkjet recording units 30 includes a plurality of inkjet recording heads 32 arranged in a direction orthogonal to the paper transport direction. In the ink jet recording head 32, a plurality of nozzles 84 are formed in a matrix. An image is recorded on the recording paper P by ejecting ink droplets from the nozzles 84 onto the recording paper P that is continuously transported through the paper transporting path 104. For example, in order to record a so-called full-color image, at least four inkjet recording units 30 are arranged corresponding to each color of YMCK.

  As shown in FIG. 3, the print area width by the nozzle 84 of each inkjet recording unit 30 is longer than the maximum sheet width PW of the recording sheet P on which image recording by the inkjet recording apparatus 10 is assumed, Image recording over the entire width of the recording paper P can be performed without moving the inkjet recording unit 30 in the paper width direction (so-called Full Width Array (FWA)). Here, the printing area is basically the maximum of the recording area obtained by subtracting the margin not to be printed from both ends of the sheet, but is generally larger than the maximum sheet width PW to be printed. This is because there is a possibility that the sheet is conveyed at an angle (skew) with respect to the conveyance direction, and there is a high demand for borderless printing.

  Next, the inkjet recording head 32 in the inkjet recording apparatus 10 configured as described above will be described in detail. FIG. 4 is a schematic diagram showing a cross-sectional configuration of the inkjet recording head 32.

  As shown in FIG. 5, the ink jet recording head 32 of the present embodiment is configured by stacking a flow path substrate 80, a piezoelectric element substrate 50, and an ink pool member 90 in this order from the lower side.

  On the flow path substrate 80, nozzles 84 for ejecting ink droplets are formed in a matrix (see FIGS. 2 and 5) at equal intervals in the scanning direction S and in the direction H perpendicular to the scanning direction. For each nozzle 84, a pressure chamber 86 communicating with the nozzle 84 is formed in a matrix (see FIG. 5), and the pressure chamber 86 is filled with ink.

  The ink pool member 90 includes a top plate 90A, a side wall member 90B, and a lower substrate 90C. The top plate 90A is provided with an ink supply port 92 which communicates with an ink tank (not shown). The ink pool member 90 constitutes a common ink pool chamber 94 having a predetermined shape and volume surrounded by the top plate 90A, the side wall member 90B, and the lower substrate 90C. Ink injected from the ink supply port 92 is stored in the common ink pool chamber 94.

  A supply hole 73 for supplying ink stored in the common ink pool chamber 94 to the pressure chamber 86 is formed in the lower substrate 90C. As shown in FIG. 5A, the supply hole 73 is formed for each pressure chamber 86. When the lower substrate 90 </ b> C is viewed in plan from the ink ejection direction and divided into two left and right regions with the center in the longitudinal direction (the direction of arrow H) as a boundary, the supply hole 73 in the left region corresponds to the left end of the pressure chamber 86. The supply hole 73 in the right region is formed at a position corresponding to the right end of the pressure chamber 86. That is, in FIG. 5A, the supply holes 73 from the left end to the sixth row are formed at positions corresponding to the left end of the pressure chamber 86, and the supply holes 73 in the seventh row to the right end from the left end are the pressure chamber 86. It is formed at a position corresponding to the right end of.

  Since the supply hole 73 is formed at the above position, the interval between the supply hole 73 in the sixth row and the supply hole 73 in the seventh row from the left end is longer than the interval between the other supply holes 73. A long interval region E1 is formed on the lower substrate 90C.

  As shown in FIGS. 4 and 5B, the ink pool member 90 is provided with a reinforcing member 96 that reinforces the strength of the ink pool member 90. The reinforcing member 96 is disposed so as to cross the ink pool member 90 in the long interval region E1, and is joined to the side wall member 90B. The reinforcing member 96 is also joined to the top plate 90A, and divides the common ink pool chamber 94 into two pool chambers. The width W of the reinforcing member 96 in the arrow H direction is substantially the same as the distance between the supply holes 73 on both sides of the long interval region E1.

  According to the above configuration, the supply holes 73 are not arranged at equal intervals in the direction of the arrow H, but are arranged at different pitches. Therefore, the supply holes 73 are not configured when arranged at equal intervals. A wide long-interval region E1 can be formed. By providing the reinforcing member 96 in the long interval region E1, the thickness of the reinforcing member 96 in the arrow H direction can be increased, and the ink pool member 90 can be effectively reinforced.

  A drive IC 77 is mounted on the lower surface of the lower substrate 90C. The drive IC 77 is disposed at the end of the lower substrate 90C so as not to face a piezoelectric element 54 described later, and is housed between the piezoelectric element substrate 50 and the lower substrate 90C.

  In addition, metal wiring (not shown) for energizing the drive IC 77 is formed on the lower surface of the lower substrate 90C.

  The piezoelectric element substrate 50 includes a vibration plate 52 and a piezoelectric element 54. The diaphragm 52 is disposed on the upper side of the flow path substrate 80 and constitutes the upper part of each pressure chamber 86. The diaphragm 52 is formed of a metal such as SUS, has elasticity in at least the vertical direction, and is configured to bend and deform (displace) in the vertical direction when the piezoelectric element 54 is energized (when a voltage is applied). It has become. The diaphragm 52 may be an insulating material such as glass. The piezoelectric elements 54 are arranged in a matrix and are provided for each pressure chamber 86 so as to cover the pressure chamber 86 when viewed in plan. A lower electrode having one polarity is disposed on the lower surface of the piezoelectric element 54, and an upper electrode having the other polarity is disposed on the upper surface of the piezoelectric element 54.

  Bumps 78 are connected on the upper electrode of the piezoelectric element 54. By this pump 78, the drive IC 77 and the piezoelectric element 54 are electrically connected via a metal wiring. This eliminates the need for individual wiring on the piezoelectric element substrate 50. A voltage is applied from the driving IC 77 to the piezoelectric element 54 at a predetermined timing, and the diaphragm 52 is bent and deformed in the vertical direction, whereby the ink filled in the pressure chamber 86 is pressurized, and an ink droplet is ejected from the nozzle 84. Discharge.

  A supply hole 50 </ b> A communicating with the pressure chamber 86 is formed in the diaphragm 52. The supply hole 50A is a fine and precise hole and has a function of adjusting the flow path resistance of the ink.

  As shown in FIG. 4, on the upper side of the supply hole 50A, there is provided a rib partition wall 68 that constitutes a supply path 68A that communicates with the supply hole 50A and also communicates with the supply hole 73 of the lower substrate 90C. The supply path 68 </ b> A configured by the rib partition wall 68 is in communication with each of the supply holes 73 formed in the lower substrate 90 </ b> C of the ink pool member 90.

  Further, the rib partition wall 68 forms a hollow between the piezoelectric element substrate 50 and the ink pool member 90 (lower substrate 90C). Due to this hollow, the displacement of the piezoelectric element 54 is not hindered, and the piezoelectric element 54 can be isolated from the ink.

  Next, the operation of the inkjet recording apparatus 10 including the inkjet recording head 32 having the above-described configuration will be described. First, when an electrical signal for instructing printing is sent to the inkjet recording apparatus 10, one recording sheet P is picked up from the stocker 24 and conveyed to the recording unit 20 by the conveying device 26.

  On the other hand, in the ink jet recording unit 30, ink has already been injected (filled) from the ink tank into the common ink pool chamber 94 of the ink jet recording head 32 via the ink supply port 92, and the ink filled in the common ink pool chamber 94 is The pressure chamber 86 is supplied (filled) through the supply hole 73, the supply path 68A, and the supply hole 50A. At this time, a meniscus in which the ink surface is slightly recessed toward the pressure chamber 86 is formed at the tip (ejection port) of the nozzle 84.

  An image based on the image data is recorded on the recording paper P by selectively ejecting ink droplets from the plurality of nozzles 84 of the ink jet recording head 32 while the recording paper P is transported at a predetermined transport speed. That is, a voltage is applied to a predetermined piezoelectric element 54 at a predetermined timing by the drive IC 77, the diaphragm 52 is bent and deformed in the vertical direction (vibrated out of plane), and the ink in the pressure chamber 86 is pressurized. Then, an image is formed by ejecting ink droplets from a predetermined nozzle 84.

  The recording paper P is conveyed toward the discharge unit 22 while forming an image, and is discharged to the tray 25 by the paper discharge belt 23. Thereby, the printing process (image recording) on the recording paper P is completed.

  In the present embodiment, an example in which only one reinforcing member 96 is disposed at the center of the ink pool member 90 has been described. However, a plurality of reinforcing members 96 may be disposed.

  For example, as shown in FIG. 6A, the formation position of the supply hole 73 is switched to the position corresponding to the left end of the pressure chamber 86 and the position corresponding to the right end for every three rows, and the third and fourth rows from the left end. And a long interval region E2 is formed at two positions between the third row and the fourth row from the right end. Thereby, as shown in FIG. 6B, two reinforcing members 96 can be disposed in the long interval region E2.

  Further, as shown in FIG. 7A, the formation position of the supply hole 73 is switched for each column between a position corresponding to the left end and a position corresponding to the right end of the pressure chamber 86, and the second and third columns from the left end. Between the 4th and 5th columns from the left end, between the 6th and 7th columns from the left end, between the 8th and 9th columns from the left end, and the 10th and 11th columns from the left end A long interval region E3 is formed at five points between the two. Accordingly, as shown in FIG. 7B, five reinforcing members 96 can be arranged in the long interval region E3.

  In the above embodiment, the reinforcing member 96 is joined to the top plate 90A and the side wall member 90B to divide the common ink pool chamber 94 into a plurality of pool chambers, but the reinforcing member 96 is not necessarily limited to the top plate 90A and the side wall. It is not necessary to be joined to the member 90B, and it may be merely in contact. By doing so, the top plate can be easily deformed flexibly, and a damper function for effectively attenuating even if a pressure wave generated in the pressure chamber at the time of discharge driving is mixed in the pool is enhanced, and an effect of reducing crosstalk can be obtained. . Furthermore, as shown in FIG. 8, the reinforcing member 96 may be separated from the side wall member 90B so as to function as a current plate. As a result, the flow of ink in the common ink pool chamber 94 can be made smooth, air bubbles and mixed dust can be better removed, and ink consumption during ink filling work can be reduced.

As another example, the reinforcing member 96 is joined to the side wall member 90B to divide the common ink pool chamber 94 into a plurality of pool chambers. In each of the pool chambers, the reinforcing member 96 is separated from the side wall member 90B to form a current plate. It can also be a combination provided. According to this configuration, it is possible to achieve both the effect of smoothing the flow of ink by the rectifying plate and the effect of uniforming the characteristics due to the small difference in flow path resistance. When 73 is arranged at the left end with respect to the pressure chamber 86, the distance from the nozzle 84 is longer than that at the right end, so that the nozzle 84, the pressure chamber 86, and the supply hole 73 are arranged. Although the relative position has changed, the relative positions of the nozzle 84, the pressure chamber 86, and the supply hole 73 can be prevented from changing even if the position of the supply hole 73 with respect to the pressure chamber 86 is changed.

  For example, as shown in FIG. 9, when the inkjet recording head is viewed in plan from the ink ejection direction, a nozzle 84 is disposed at the top of a substantially isosceles triangle and supplied to the left or right of the base corner of the isosceles triangle. By forming the hole 73, the relative positions of the nozzle 84, the pressure chamber 86, and the supply hole 73 can be prevented from changing. With this configuration, it is possible to reduce variations in droplet discharge characteristics due to different relative positional relationships.

  In this embodiment, the example of the FWA corresponding to the paper width has been described. However, the ink jet recording head of the present invention is not limited to this, and is applied to a partial width array (PWA) apparatus having a main scanning mechanism and a sub-scanning mechanism. Can also be applied. In particular, since the present invention is effective for realizing a high-density nozzle arrangement, it is suitable for FWA that requires one-pass printing.

  In addition, in the inkjet recording apparatus 10 of the above-described embodiment, the inkjet recording units 30 of black, yellow, magenta, and cyan are mounted on the carriage 12 and selectively selected from the inkjet recording heads 32 of these colors based on image data. Although ink droplets are ejected and a full-color image is recorded on the recording paper P, ink jet recording in the present invention is not limited to recording characters and images on the recording paper P.

  That is, the recording medium is not limited to paper, and the liquid to be ejected is not limited to ink. For example, industrially used liquids such as creating color filters for displays by discharging ink onto polymer films or glass, or forming bumps for component mounting by discharging welded solder onto a substrate The ink jet recording head 32 according to the present invention can be applied to all droplet ejecting apparatuses.

1 is a schematic diagram illustrating an overall configuration of an ink jet recording apparatus according to an embodiment. It is the schematic which shows arrangement | positioning of the inkjet recording unit of this embodiment. It is a figure which shows the printing area | region by the inkjet recording unit of this embodiment. It is sectional drawing which shows the structure of the inkjet recording head of this embodiment. 4A is a plan view of a common ink pool chamber member of the ink jet recording head of the present embodiment, and FIG. It is a figure which shows the modification of the common ink pool chamber member of the inkjet recording head of this embodiment. It is a figure which shows the other modification of the common ink pool chamber member of the inkjet recording head of this embodiment. It is a figure which shows the other modification of the common ink pool chamber member of the inkjet recording head of this embodiment. It is a figure which shows the other modification of the common ink pool chamber member of the inkjet recording head of this embodiment. It is a schematic sectional drawing which shows the structure of the inkjet recording head in which the nozzle and the supply hole are arranged at equal intervals. It is a schematic plan view showing the structure of an ink jet recording head in which nozzles and supply holes are arranged at equal intervals.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet recording device 32 Inkjet recording head 50 Piezoelectric element substrate 50A Supply hole 52 Diaphragm 54 Piezoelectric element 68 Rib partition wall 68A Supply path 73 Supply hole 80 Channel substrate 84 Nozzle 86 Pressure chamber 90 Ink pool member 90C Lower substrate 90B Side wall member 90A Top plate 94 Common ink pool chamber 96 Reinforcement member E1 Long interval region E2 Long interval region E3 Long interval region

Claims (7)

A plurality of nozzles arranged at equal intervals in a predetermined direction and ejecting droplets;
A pressure chamber communicating with each of the plurality of nozzles and filled with a liquid;
A common pool chamber member configured to store a liquid to be supplied to the plurality of pressure chambers, and having a plurality of supply holes for supplying liquid to each of the pressure chambers;
A reinforcing member for reinforcing the strength of the common pool chamber member;
With
The long interval supply holes of at least some of the plurality of supply holes are arranged at positions where the distance from one adjacent supply hole is longer than the distance from another adjacent supply hole. A droplet discharge head, wherein a long interval region is formed between the hole and the adjacent one supply hole, and the reinforcing member is disposed in the long interval region of the common pool chamber member.   The droplet discharge head according to claim 1, wherein the plurality of nozzles are arranged in a matrix.   3. The liquid according to claim 2, wherein at least one row of the supply holes is the long interval supply hole, and the reinforcing member is disposed so as to cross a width direction of the common pool chamber member. Drop ejection head.   The droplet discharge head according to claim 3, wherein the reinforcing member is a partition that divides the common pool chamber into a plurality of pool chambers.   The droplet discharge head according to claim 3, wherein the reinforcing member is a current plate that forms a liquid flow path in the common pool chamber.   The relative positional relationship between the nozzle, the pressure chamber communicated with the nozzle, and the supply hole for supplying the liquid to the pressure chamber is the same in all combinations when viewed from the droplet discharge direction. The droplet discharge head according to any one of claims 1 to 5.   A droplet discharge device comprising the droplet discharge head according to claim 1.

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